Conventionally, several proposals have been made for a winching and drawing machine, in which a number of parts is small and which is relatively simple in construction. A winching and drawing machine shown in FIG. 20, for example, provides an idler grip that adjusts a chain length.
Adjustment of the chain length by use of a conventional idler grip will be described below with reference to FIG. 20.
The winching and drawing machine shown in FIG. 20 comprises a drive member 35 screwed on a drive shaft 31 so as to be able to advance and retreat, an opening 37 through which extends the drive shaft 31 and which is capped, an idler grip 41 provided at an end of the drive shaft 31, a spring 40 installed between the idler grip 41 and the drive shaft 31 to elastically bias the drive member 35 in a direction away from brake plates 33, and a restriction member 39 that restricts rotation of the drive member 35.
In a winching and drawing machine of this type, the idler grip 41 is held by screws against screw holes provided on a projecting portion 38 of the drive member 35, and peripheral concave grooves 36 for mounting of a handle 43 are provided on an outer peripheral surface of the drive member 35 where the drive member 35 contacts the idler grip 41. Also, the restriction member 39 is biased toward a step 31a of a male thread portion of the drive shaft 31 by the spring 40 so as not to project from the opening 37 of the drive member 35, and also the drive member 35 is biased by the spring 40 via the idler grip 41 in a direction away from the brake plates 33. Also, a projecting portion 39a of the restriction member 39 and the projecting portion 38 of the drive member 35 abut each other to restrict rotation of the drive member 35 relative to the drive shaft 31.
When the winching and drawing machine is operated under a load, the handle 43 is repeatedly swung in a winching-up direction to rotate the drive member 35 whereby torque is transmitted to the drive shaft 31 via the brake plates 33, a brake bearing member 32, and the like to rotate a load sheave in a winching-up direction to winch up a chain.
Also, when the handle 43 is repeatedly swung in a winching-down direction, the chain is winched down and when there is no load, the drive member 35 is released from the brake plates 33 due to action of the spring 40, so that the load sheave, around which the chain is wound, is put in an idling state capable of idling. When a load is applied to the chain during this time of idling, a screwing action generates a pressing force of the drive member 35 on the brake plates 33 to cause a braked state, so that rotation of the load sheave in the winching-down direction is prevented. Also, while adjustment of the chain length at the time of idling can be performed by directly pulling the chain, it can be also performed by turning the idler grip 41 to rotate the drive member 35.
Since the winching and drawing machine described above is provided with the restriction member 39 fitted into a splined portion of the drive shaft 31 in order to restrict rotation of the drive member 35, it is necessary to spline the drive shaft 31 and the restriction member 39, and it is necessary to provide the projection 39a on the restriction member 39 and to provide the projection 38, with which the projection 39a is to abut, inside of the drive member 35. Further, since the idler grip 41 is screwed against the screw holes provided on the drive member 35, it is necessary to form screw holes on the drive member 35 and the drive member 35 must have a certain degree of thickness in order to have the screw holes possessing strength, so that the drive member 35 is increased in diameter with a result that a fitting opening of the lever 43 becomes large in diameter and causes a disadvantage in that the winching and drawing machine in its entirety must be large in size.
Also, there are known a construction in which a handle is fitted onto a drive member and a retaining washer is provided on an end of a drive shaft where it is latched to a retaining member, and a construction in which a nut is fitted onto an end of a drive shaft and the end of the drive shaft is latched by a retaining pin. However, both such washer and nut are provided to prevent coming-off but do not use an idler grip which would perform adjustment of a chain length so that direct contact with a chain would be unnecessary.
Also, regarding the drive member of a winching and drawing machine, it is conventional that an idler spring is installed on the drive shaft at that side of the drive member on which brake plates are fitted and mounted, and at time a of winching-up operation, a lever handle is repeatedly rotated, thereby moving the drive member against the idler spring toward the brake plates to bring a brake bearing member into pressure contact with a bearing holding stepped portion of the drive shaft to transmit rotation of the drive member to the drive shaft to turn a load sheave. Also, when there is no load, the drive member is biased by the idler spring in a loosening direction and the brake plates or the like are released, so that it is possible to operate the chain freely.
With the winching and drawing machine of the conventional type, since the idler spring has the same diameter where it is mounted on the side toward the drive member and where it is mounted on the side toward the brake plates of the drive shaft, a step having a larger diameter than that of the idler spring is provided on that portion of the drive shaft with which the idler spring engages in order to cause engagement of the idler spring, so that the drive shaft is increased in diameter, parts such as brake plates mounted on the drive shaft, and the like are increased in inside diameter, and respective parts are correspondingly increased in external shape, which is responsible for enlargement of a main body of the winching and drawing machine.
Further, with a conventional winching and drawing machine provided with load-side and non-load side guide rollers that guide a chain wound around a load sheave, these respective guide rollers are independent as single parts from other parts to be mounted on a frame, so that they constitute an obstacle in making a winching and drawing machine small in size and involve a problem in that they are large in weight and expensive.
A construction of guide rollers of a conventional winching and drawing machine will be described below with reference to FIG. 21.
In this figure, reference numeral 50 denotes a load sheave, 51 a pinion gear to mesh with a load gear (not shown), 52a a load-side guide roller contacting an outer side of load-side chain and guiding the load-side chain from outside, 52b a non-load side guide roller, 53 a frame, 54 a chain, and 55 a drive shaft.
The pinion gear 51 is provided at an end of the drive shaft 55 and driven by known drive structure such as a drive member, brake plates, a brake bearing member, a multiple thread, and the like. When the pinion gear 51 is driven, the load sheave 50 is rotated via a load gear (not shown) which meshes with the pinion gear to winch up the chain 54. When the load sheave 50 operates to winch up the chain 54, the chain 54 is guided by the load-side and non-load side guide rollers 52a, 52b so that the chain is prevented from detaching from the load sheave 50. In this manner, the guide rollers 52a, 52b are mounted as single parts on the frame 53.
Further, as structure related to the chain guide, a link chain paid out toward the non-load side from the load sheave has a problem in that at a time of winching-up of the chain, it is sent to the non-load side while still being wound around the load sheave, fitted into the groove of the load sheave. In order to solve the problem, as shown in FIGS. 22(a) and 22(b), there is known an arrangement described in, for example, JP-A-5-123794, in which a chain guide comprising a non-load side guide 14a disposed close to load sheave 10 and having a groove 14c for guiding vertical links 30b, and an inner guide 60 in the form of a flat plate having a guide plane 60a arranged so that link chain 30 is interposed between it and the non-load side guide 14a to guide the link chain 30, is provided on a non-load side of the winching and drawing machine, and among links in the non-load side chain 30 paid out from the load sheave 10, transverse links 30a fitted into a load sheave groove following vertical links 30b are separated from the load sheave groove by projection 60b, which is provided on a tip end of the inner guide 60 and pushes out the vertical links 30b away from the load sheave, that is, outside the load sheave 10, whereby winding of the transverse links 30a around the load sheave is restricted.
When using a chain guide of this type to take an action of winching down a link chain, that is, in a case where the link chain 30 is to be forwarded to a load side from a non-load side, the link chain 30 is forwarded to the load side of the load sheave 10 while the vertical links 30b are guided by the groove 14c of the non-load side guide 14a and restrained by the guide plane 60a of the inner guide 60.
However, while an action of forwarding the link chain 30 is smoothly performed in a case where the vertical links 30b are forwarded in a state of being fitted into the groove 14c of the non-load side guide roller 14a at a time of forwarding the link chain 30, there occurs a case where the link chain 30 is twisted as shown in FIG. 22(b), whereby the vertical links 30b are not fitted into the groove 14c of the non-load side guide roller 14a, and the link chain 30 is forwarded to the load sheave 10 in a state of being squeezed between the non-load side guide roller 14a and the guide plane 60a of the inner guide 60. In this case, the link chain 30 is caught by the non-load side guide roller 14a between the non-load side guide roller 14a and the load sheave 10, so there is no smooth winching action of the link chain by the load sheave 10.
In order to solve this problem, a chain guide has been developed (for example, see JP-A-6-155325), in which a guide member 61 for guiding vertical links 30b and transverse links 30a with use of a cross-shaped guide 61a is provided on a non-load side of a winching and drawing machine as shown in FIGS. 23(a) and 23(b) to prevent generation of twisting of a link chain 30 at a time of an action of forwarding the link chain 30.
However, the construction described in JP-A-6-155325 involves a problem in that it is complicated in working and parts are high in cost since a guide surface has cross-shaped concavities and an entire construction is one unit.
Next, a load gear and a load sheave are conventionally connected together by use of splines or serrations provided on a sheave shaft as shown in FIGS. 24 and 25.
Conventional connection structure for a load gear and a load sheave will be described below.
In FIGS. 24 and 25, reference numeral 70 denotes a drive shaft, and 70a a pinion, with both members, respectively, being supported by bearings. Reference numeral 71 denotes a load sheave, and 72 a sheave shaft provided at an end of the load sheave 71, with both members, respectively, being supported by bearings 75. Reference numeral 73 denotes a load gear connected to the sheave shaft by use of splines orserrations, with the load gear meshing with the pinion 70a to transmit rotation of the drive shaft 70 to the load sheave 71 to rotate the load sheave 71. The pinion 70a, the load gear 73, and the sheave shaft 72 are covered by a gear casing 74. The sheave shaft 72 of the load sheave 71 is provided, as shown in FIG. 25, with splines 72d with which the load gear 73 meshes. Such structure is known in JP-B-63-3834.
Since working of grooves for the splines 72d is performed by cutting/rolling, it is necessary to provide on the sheave shaft 72 a relief area where a cutting tool can extend safely. Therefore, the conventional sheave shaft 72 needs a relief 72e, which is disposed between an end of the splines 72d and a front face 72c of the sheave shaft 72 as shown in FIGS. 24 and 25. The relief 72e does not function for fitting of the load gear 73 directly, so that the load gear becomes wider by a width of the relief 72e, and the pinion which meshes with the load gear 73, reduction gears, and the like are also increased in thickness, which leads to an increase in width of the winching and drawing machine and constitutes an obstacle in making the winching and drawing machine small in size and lightweight. Also, since working of grooves for the splines is performed by cutting/rolling as described above, there is caused a problem in that working is increased in cost and number of steps.
Also, since a body frame of a winching and drawing machine is conventionally fixed by bolts and nuts, steps for assembly are increased to cause an obstacle in miniaturization. Conventional fixation structure for a body frame will be described below with reference to FIG. 26.
In FIG. 26, a load sheave 89 is provided between a pair of frames 84 that are positioned by steps of a bolt 85 to keep a predetermined spacing therebetween, small-diameter portions at both ends of the bolt 85 are fitted and inserted into holes provided on the frames 84, and the small-diameter portions at the both ends are threaded and clamped by nuts 86.
Brake plates 87, and a brake bearing member 88 are covered by a brake cover 83, and an outside of the frame 84 toward the load sheave 89 is covered by a cover 82.
With this conventional winching and drawing machine, the small-diameter portions at both ends of the bolt 85 are fitted and inserted into the holes provided on the frames 84 and the holes provided on the frames 84 are set to be slightly larger in diameter than the threaded portions at both ends of the bolt 85 so as to allow threaded portions at the both ends to go through the holes. Therefore, there are slight gaps between the threaded portions at both ends of the bolt 85 and the holes of the frames 84 even when the bolt 85 is clamped by the nuts 86 and the frames 84, the brake cover 83, and the gear casing 82 are fixed together, so that dislocation such as offset, or the like, is in some cases generated corresponding to these gaps in a case where the winching and drawing machine is given a large shock during operation.
Also, since both ends of the bolt 85 are clamped by the nuts, one end of the bolt is given a nut and then the body must be reversed to give the other end of the bolt the other nut, so that more assembly steps are needed for such action. Further, since tip ends of the bolt and the nuts are exposed outside the body, rust is generated and damage is liable to be caused, in which case disassembly for maintenance becomes difficult. Also, there is a need of providing a space, which allows motion of a nut mounting tool such as spanner, or the like for screwing the nut, on the brake cover 83 and the gear casing 82, which constitutes an obstacle to miniaturization.
In view of respective problems described above, the invention provides a winching and drawing machine, of which miniaturization and lightening are achieved and which is durable and easy to assemble and disassemble.